Gallium nitride (GaN) power transistors, whether on silicon or silicon-carbide (SiC) substrates, have made “noise” lately for their many claims of ruggedness, high power density, and high efficiency. Cree, often associated with light-emitting-diode (LED) products, is also a leading supplier of high-power GaN-on-SiC devices. The company recently added several packaged discrete GaN high-electron-mobility-transistor (HEMT) power parts and one GaN monolithic-microwave-integrated-circuit (MMIC) high-power amplifier, all well suited for applications at S-band (2.7 to 3.5 GHz) frequencies.

Debuting at the 2011 IEEE International Microwave Symposium (IMS), the devices, as per their maker, offer the industry’s best-known combination of power and efficiency. They reach typical power-added efficiencies (PAEs) of 60%, translating into a power-consumption reduction up to 20% over comparable devices. The discrete devices, models CGH31240F and CGH35240F, are internally matched to 50 Ω and provide saturated RF output power of 240 W over bandwidths of 2.7 to 3.1 GHz and 3.1 to 3.5 GHz, respectively. The devices deliver large-signal gain in excess of 11 dB, which is deemed fairly impressive due to their compact footprints, each measuring 0.9 in. x 0.68 in. (see figure). The two GaN power transistors exhibit a pulse droop of less than 0.2 dB under specified operating conditions, credited to their high efficiency and the unique thermal properties of GaN on SiC.

Also announced at IMS 2011, model CMPA2735075F is a two-stage GaN HEMT MMIC amplifier. The device delivers saturated RF output power of 75 W from 2.7 to 3.5 GHz with 20-dB gain. The CMPA2735075F resides in a small package measuring 0.5 in. x 0.5 in. According to the company, it is the first and only S-Band GaN HEMT MMIC high-power amplifier offering a 60% typical PAE with RF pulse widths of 300 μs and a 20% duty cycle.

All three devices are currently available for purchase. To review their datasheets, visit http://www.cree.com/products/pdf/CGH31240F.pdf, http://www.cree.com/products/pdf/CGH35240F.pdf, and http://www.cree.com/products/pdf/CMPA2735075F.pdf. For additional information, visit http://www.cree.com/rf.

Cree
4600 Silicon Dr.
Durham, NC 27703
(919) 313-5300, (800) 533-2583
FAX: (919) 313-5558
www.cree.com

LI-Ion Batteries Help Uavs Fly

Yardney Technical Products, a company noted for its presence in the military, aircraft, and aerospace markets, has proven the vitality of li-ion battery technology in one of the US Navy’s reconnaissance aircraft. The first flight of the tailless, unmanned X-47B air vehicle AV-1 earlier this year from Edwards Air Force Base in California carried Yardney batteries, identical to those used on the highly successful Global Hawk reconnaissance aircraft (see figure). The li-ion batteries were used to provide emergency power in the event of an engine failure. Several years ago, the company worked solidly with prime contractor Northrop Grumman to develop the high energy backup batteries for the Global Hawk. In turn, the X-47 team was able to seamlessly integrate the design into the unmanned aircraft without modification.

The company’s li-ion batteries are characterized by a number of features that make them strong contenders in meeting the stringent requirements of the military and aerospace arenas. These include an energy density of 358 Wh/l, a specific energy figure of 145 Wh/kg, an operating life of 2,100 deep cycles, discharge capabilities the likes of a continuous 10 C rate and a 50 C pulse rate, a rapid C rate recharge capability, operating temperature range from -40° to +65°C, and a true prismatic design. In addition to its lithium-ion product line, Yardney offers silver-zinc and metal-air cells and batteries. For further information, visit http://www.yardney.com/Lithion/lithion.html or http://www.lithion.com.

Yardney Technical Products
82 Mechanic Street
Pawcatuck, CT 06379
(860) 599-1100, FAX: (860 599-3909
www.yardney.com